1. Technical Field
The present invention relates to fountain toothbrushes having a built-in toothpaste reservoir and dispenser and, more particularly, to such fountain toothbrushes wherein the toothpaste is maintained under constant pressure so as to be selectively dispensed in response to actuation of a valve.
2. Discussion Of The Prior Art
It is well-known in the prior art to provide a toothbrush having a handle in the form of a reservoir for toothpaste that may be selectively dispensed. Such toothbrushes tend to fall into two categories, namely: those in which the toothpaste is normally not under pressure but is selectively pressurized to dispense the paste; and those in which the paste is under constant pressure and is dispensed by actuation of a valve. The former category is exemplified by the following patents: U.S. Pat. No. 2,226,663 (Hill et al); U.S. Pat. No. 995,626 (Moran); U.S. Pat. No. 4,693,622 (Booth); U.S. Pat. No. 3,995,648 (Kuryla); U.S. Pat. No. 4,269,207 (Konrad et al); U.S. Pat. No. 4,530,369 (Adams); U.S. Pat. No. 1,653,987 (Cliffe); U.S. Pat. No. 2,416,684 (Fischer); U.S. Pat. No. 2,441,520 (Ulvick); and U.S. Pat. No. 4,695,177 (Kuo). These pump-type devices all suffer from the disadvantage of inefficient evacuation of the paste reservoir, thereby resulting in significant amounts of wasted paste that cannot be pumped from the reservoir. In addition, the pump-type units usually require two hands to operate and thereby are no more convenient in use than a toothpaste tube and a separate brush.
Examples of toothbrushes with continuously pressurized paste reservoirs are found in U.S. Pat. Nos. 3,937,235 (Broughton) and U.S. Pat. No. 2,987,743 (Capps). In the Broughton patent the reservoir is pressurized by means of a plastic bag containing freon gas under pressure, the gas expanding the bag to pressurize the surrounding paste as the paste is dispensed. This arrangement is inefficient because the plastic bag tends to rollingly expand over some of the paste, trapping the paste against the reservoir wall and preventing it from being dispensed. The Capps patent discloses a reservoir wherein the paste is mixed with freon gas under pressure in the reservoir so that the gas and paste are dispensed together in response to actuation of a valve. The mixing of the gas and paste adds significantly to manufacturing time and cost. Moreover, the gas tends to discharge from the mixture before all of the paste is dispensed, thereby leaving a considerable amount of wasted paste in the reservoir. The Capps valving mechanism is somewhat easier to operate than the Broughton valve but requires that a spring be disposed directly in a toothpaste flow path with the result that the paste tends to collect on the spring and clog the dispensing path. In addition, actuation of the valve to dispense the toothpaste in the Capps arrangement requires movement of the toothpaste head relative to the reservoir/handle. This movement is not easily effected and, in any event, requires the use of both hands. The Capps valving mechanism itself requires a relatively complex set of parts, thereby adding to the overall manufacturing cost of the device. The cost of the product is also increased by the cost of the freon gas employed as the paste pressuring agent. Additionally, the possibility of the freon gas contaminating the toothpaste renders the Capps arrangement somewhat less than desirable.